Dry process for the manufacture of cement



March 31, 1931.

M. VOGEL-JORGENSEN DRY PROCESS FOR THE MANUFACTURE OF CEMENT Filed Sept. 23. 1927 I avwewbo'c KA /MW 7 4 Patented Mar. 31,1931

UNITED STATES PATENT OFFICE MlKAEL VOGEL-JORGENSEN, OF FREDERIKSBERG, NEAR COPENHAGEN, DENMARK, AS-

-SIGNOR TO I. L. SMIDTH & 00., OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY DRY PROCESS FOR THE MANUFACTURE OF CEMENT Application filed September 23, 1927, Serial No. 221,454, and in Norway June 27, 1927.

The present invention relates to the making of a homogeneous mixture of a given composition of dry pulverulent raw materials which, in their natural state vary con- 5 siderably in composition. In the manufacture of cement by the burning of raw cement meal in the dry process it is exceedingly difficult to obtain a raw meal of uniform composition. Although the dry process is quite economical from the standpoint of fuel consumption it has not been adopted universally because of this difficulty. A uniform composition of the raw meal burned is of the greatest importance, not only in obtaining a good 5 quality of cement and economical burning, but also to insure a satisfactory durability of the kiln lining.

The difficulty, heretofore experienced, of securing homogeneity of the material in a single storage binhas caused great trouble and expense by reason of the methodsemployed in mixing the material to attain the desired uniformity.

The difliculties outlined above are rendered the more baffling because the raw materials, in the natural state in which they are found, vary considerably in composition. For instance, the percentage content of the carbonate of calcium, oxide of magnesium, silicic acid, etc., varies often as much as 4% or even more. Although care is taken that the raw materials to be ground together into raw meal are fed into the mill, as far as possible, in the right proportion according to the chemical composition of the materials, the said variation of the, properties of the dry raw materials causes the raw meal leaving the mill at different times to lack uniformity of composition. Consequently, the bin in which the dry raw meal is received may have portions of its contentsof a different composition from other portions and, heretofore, it has been necessary to draw the meal from the bottom and return it at the top so as to cause the meal to circulate therethrough repeatedly, in order that the desired homogeneity may be secured. Not until this homogeneity has been secured in each individual bin will it be possible to correct the composition of the dry raw meal, which is fed to the kiln, by mixing the meal from the various bins. The purpose of the present invention is to overcome these difficulties in connection with the treatment of dry pulverulent mixtures and, more particularly, contemplates the effective homogenization of the'dry meal in the individual bins before correcting the mixture for the final raw meal.

It is contemplated, therefore, to combine the mechanical stirring of the dry pulverulent contents of a bin with the admixture of a sufficient quantity of air to render the contents thereof sufficiently mobile to permit the mechanical stirring to be more effective.

The improved method may be briefly described as follows.

An amount of air is added to two lots of raw material which may be of somewhat different composition, the air being supplied to the extent, and in such a way, that homogenization of each lot may be eflected by mechanical stirring carried on simultaneously. After this stirring has taken place, and the contents of each bin rendered uniform, the dry raw meals from these different lots are mixed and homogenized-in the ratio required to obtain a homogeneous raw meal of the composition desired. b

Figure 1 shows, in transverse vertical section, bins and mixing apparatus which may be employed in the Figure 2 is a view in section, taken on line 2-2 of Figure 1. g

Referring particularly to the drawing, the reference character a designates a conveyor and distributing means which carries the raw material from the mill plant to the mixing bins. The conveyors discharge the material into bins b, from, which a distributor 0 carries it to mixing bins at through chutes 0. Within the mixing bins d, mechanical stirrers d are provided and during the operationof the mechanical .stirrers, air under pressure method described herein.

from any suitable source, is injected into the bin through suitable nozzles (Z Pipe line 2' carries air under pressure to the various stirrers from compressor 2''. and suitable driving motors 2' are provided to rotate the stirrers.

A portion of the material may be carried to a smaller bin 6. also provided with the homogenizing means described above from which samples can be taken from time to time at e.

For this purpose, a conveyor e is provided,

communicating with bins d at e and e.

After the material in the several bins d has been thoroughly mixed and rendered of uniform quality, it is then discharged into one of the bins 9, through conveyors j, j and j the quantities taken from the respective bins d being such that the resulting dry raw meal will have the desired composition. In the bin g the homogenization of the mixture is effected in the same manner as before, that is, by mechanical stirring with the admixture of air. From the bins g the raw meal may be carried to storage bins b means 0f conveyors h and fed thence to the ilns as needed. Y

I claim as my invention:

A method for mixing dry pulverulent cement making materials to form a homogeneous mass of a composition required for manufacturing cement which consists in subjecting the materials in different lots to mechanical stirring with simultaneous admixture of air until the materials of the respective lots are of uniform homogeneity and thereafter .bringing together quantities of material from a plurality of the lots so brought separately to uniform homogeneity and subjecting the mass so brought together to mechanical stirring with simultaneous admixture of air.

This specification signed this 17th day of August, A. D. 1927.

1 LHKAEL VOGEL-JORGENSEN. 

